The present invention relates to a mat fastener that reinforces a mat hole and prevents tearing thereof. The mat hole is formed in a floor mat for automobiles and defines an anti-displacement hole.
It is known in the prior art to use a metal grommet (eyelet) type mat fastener. As a mat fastener for reinforcing and preventing tearing of an anti-displacement mounting hole formed in a floor mat for automobiles. In order to recycle or reuse the mat, it is required to remove such metal grommet type mat fasteners from the mat in advance. This is necessary because the metal grommet type mat fasteners might damage blades of a shredding machine during shredding the mat. Also, it is particularly difficult to remove the metal grommet type mat fasteners in advance. However, if the grommet is formed of a resin material, the mat can be advantageously shredded with such resin grommets mounted thereto.
The prior art teaches a mat fastener formed of a material free from any dioxin formation, such as polypropylene (PP). Typically, a mat for automobiles comprises an upper carpet layer made of olefin-based wool yam and a lower rubber base layer. If a mat fastener is made of polypropylene being a similar olefin-based material, shredder dusts can be advantageously recycled without any material separation process. Unfortunately, among various resin materials, polypropylene has a lower elastic modulus and is subject to plastic deformation. This undesirably provides insufficient fastening force to the mat. Therefore, such a mat fastener has a remaining need for improving the fastening force to the mat. U.S. Pat. No. 5,511,283, and other prior art devices disclose various types of fasteners for use as a mat or carpet fastener. However, these types of fasteners do not include any arrangement for the recycling as described above, and have a remaining need for improving a force for clamping or sandwiching both surfaces of the mat or carpet.
It is therefore an object of the present invention to provide a mat fastener having enhanced fastening force to a mat even if the fastener is made of a resin material, such as polypropylene, which has a low elastic modulus and is subject to plastic deformation.
In order to achieve the above object, according to the present invention, there is provided a mat fastener comprising a male grommet made of a resin material and a female grommet made of a resin material. The female grommet includes an outer tube portion having opposite open ends and is adapted to be inserted into a hole formed in a mat, and a flange which is formed at the outer periphery of one of the ends of the outer tube portion and is adapted to be in contact with one of the side surfaces of the mat. The male grommet includes an inner tube portion having opposite open ends and is adapted to be inserted into the outer tube portion, and a flange which is formed at the outer periphery of one of the ends of the inner tube portion of the female grommet and is adapted to be in contact with the other side surface of the mat. Each of the outer and inner tube portions is provided with engagement means for coupling the female and male grommets to each other. One of the flanges of the grommets is adapted to be brought into contact with one of the side surfaces of the mat around the mat hole, and the other flange of the grommets is brought into contact with the other side surface of the mat, so as to attach the mat fastener to the mat by sandwiching the mat between the flanges. The mat fastener as mentioned above is characterized in that one of the flanges of the male and female grommets has a larger outside dimension than that of the other thereof, and each of the flanges has an outer peripheral portion formed in a curved shape to be directed toward the mat to allow each of the flanges to be bitten into the mat in the state when the male and female grommets are coupled to each other by the engagement means.
According to the above construction, when the mat is sandwiched by the male and female grommet flanges, the outer peripheral portion of the smaller flange bites into one of the side surfaces of the mat, and the larger flange bites into the other side surface or opposite side surface of the mat at a radially outside position with respect to the position where the smaller flange bites into the mat. This provides enhanced fastening force to the mat. Thus, even if the fastener is made of a resin material, such as polypropylene, which has a low elastic modulus and is subject to plastic deformation, a high fastening force to a mat can be maintained.
Preferably, in the above mat fastener, the flange of the female grommet is formed as a circular plate having a larger diameter than that of a circular shape of the flange of the male. Further, the outer peripheral portion of the male grommet flange may be formed in a curved shape to allow the male grommet flange to bite into the mat toward the female grommet flange, and the outer peripheral portion of the female grommet flange may be formed in a curved shape to allow the female grommet flange to bite into the mat toward the male grommet flange from the opposite side of the mat at a radially outside position with respect to the position where the male grommet flange bites into the mat. This provides enhanced fastening force to the mat in addition, each of the flanges formed in a circular dome shape takes on enhanced strength with keeping adequate resilience.
Further, the above mat fastener may include an upper carpet layer and a lower rubber base layer. In this case, the male grommet may be disposed on the side of the carpet layer, and the female grommet may be disposed on the side of the base layer.
Further, the outer peripheral portion of the female flange preferably includes a plurality of protrusions formed in the circumferential direction of the outer peripheral portion with leaving a certain distance therebetween. The protrusion is adapted to protrude toward the base layer. This provides further enhanced fastening force.
Preferably, in the above mat fastener, at least one of the female and male grommet flanges includes a pin capable of biting into the mat to prevent relative rotation between the outer and inner tube portions.